Keragaman Genotipe A2A2 Gen ß-Casein (CSN2) dan Hubungannya dengan Kualitas Susu Sapi FH Indonesia

Abstract

Tujuan penelitian ini adalah untuk mengidentifikasi keragaman genotipe A2A2 dari gen ß-casein (CSN2) pada sapi Friesian Holstein (FH) Indonesia. Sebanyak 107 sampel darah dan 21 sampel susu sapi FH dari BBPTU-HPT Baturraden dikoleksi. Sampel darah diekstraksi menggunakan kit GeneAid untuk mendapatkan genom total. Penentuan genotipe A2A2 gen CSN2 dianalisis menggunakan metode sekuensing. Frekuensi genotipe, frekuensi alel, nilai heterozigositas, dan keseimbangan Hardy-Weinberg, dihitung menggunakan program Popgen32. Perbedaan antar genotip gen CSN2 dengan produksi susu dan kualitas susu sapi FH dilakukan dengan menggunakan uji-t. Hasil penelitian ini menunjukkan bahwa gen CSN2 berdasarkan SNP rs43703011 diperoleh tiga genotipe yaitu A1A1 (57%), A1A2 (1%), dan A2A2 (42%) dengan frekuensi alel A1 sebesar 57% dan A2 sebesar 42%. Mutasi yang terjadi pada basa A (alel A1) menjadi C (alel A2) menyebabkan perubahan asam amino dari histidin menjadi prolin. Perbedaan genotipe A1A1 dengan A2A2 terhadap produksi susu harian, kadar laktosa, protein, dan lemak susu sapi FH tidak berbeda nyata (P > 0,05). Hasil penelitian ini disimpulan bahwa gen CSN2 SNP rs43703011 pada sapi FH Indonesia bersifat polimorfik akan tetapi tidak terdapat perbedaan yang nyata antara genotipe A1A1 dan A2A2 dengan produksi susu harian, kadar lemak, protein dan laktosa.

The primary objective of this comprehensive study is to examine the diversity of the A2A2 genotype of the ß-casein (CSN2) gene in Indonesian Holstein Friesian cattle and its relationship to milk production and quality. Conducted with meticulous attention to detail, this study paves the way for further research. A total of one hundred-seven blood samples and twenty-one milk samples from BHPTU- HPT Baturraden were collected using the GeneAid kit to ensure pure FH DNA isolation. The diversity of the CSN2 gene was analyzed through sequencing. The analysis results, including genotype frequency, allele frequency, heterozygosity value, and Hardy-Weinberg equilibrium, were calculated using Popgen32. The relationship between milk production and the fat, protein, and lactose content of FH genotypes A1A1 and A2A2 was assessed using a t-test. Results indicate that the CSN2 gene analysis based on SNP rs43703011 identified three genotypes: A1A1 (57%), A1A2 (1%), and A2A2 (42%), with an A1 allele frequency of 57% and an A2 frequency of 42%. This genotype variation (SNP A>C; rs43703011) results from a change from the histidine amino acid (present in the A1A1 genotype) to proline (present in the A2A2 genotype). Milk production, lactose, protein, and fat levels in FH cows with the A1A1 genotype were not significantly different (P > 0.05) compared to those with the A2A2 genotype. It can be concluded that the CSN2 gene SNP rs43703011 is polymorphic in FH cows. However, the A1A1 and A2A2 genotypes of the CSN2 gene do not differ in lactose, protein, and fat percentages. These findings emphasize the potential for further exploration in this area, especially regarding the implications of the A2A2 genotype on milk production and quality.